Bulk animal feeds containing conjugated linoleic acid

ABSTRACT

A conjugated linoleic acid is prepared in industrial scale as a hydrolyzed isomerized product for blending into bulk domestic animal feeds. The CLA-containing isomerized hydrolyzed oil from sunflower and safflower seeds has sufficiently low levels of phosphatides and sterols to permit crude processing and incorporation into feeds of an undried, undistilled oil fraction without toxic or unpalatable effects.

This is a Continuation of application Ser. No. 09/027,075 filed on Feb.20, 1998 now U.S. Pat. No. 6,042,869.

FIELD OF THE INVENTION

This invention relates to a new use of conjugated linoleic acid inanimal feeds. The conjugated linoleic acid is manufactured in anindustrial scale process from seed oils such as sunflower oil andsafflower oil, which contain non-fatty acid residues low enough to avoidfinal purification by distillation, but still pure enough to be safelyfed to animal in bulk feed.

BACKGROUND OF THE INVENTION

Processes for the conjugation of the double bonds of polyunsaturatedunconjugated fatty acids have found their main application in the fieldpaints and varnishes. Oils comprised of triglycerides of conjugatedfatty acids are known as drying oils. Drying oils have value because oftheir ability to polymerize or “dry” after they have been applied to asurface to form tough, adherent and abrasion resistant films. Tung oilis an example of a naturally occurring oil containing significant levelsof conjugated fatty acids.

Because tung oil is expensive for many industrial applications, researchwas directed towards finding a substitute. In the 1930's, it was foundthat conjugated fatty acids were present in oil products subjected toprolonged saponification, as originally described by Moore, J. Biochem.,31: 142 (1937). This finding led to the development of several alkaliisomerization processes for the production of conjugated fatty acidsfrom various sources of polyunsaturated fatty acids.

In alkali isomerization the fatty acids are exposed to heat, pressureand a metal hydroxide or oxide in nonaqueous or aqueous environments,resulting in the formation of conjugated isomers. Other methods havebeen described which utilize metal catalysts, which is not as efficientin the production of conjugated double bonds. It was found thatisomerization could be achieved more rapidly in the presence of highermolecular weight solvent. Kass, et al., J. Am. Chem. Soc., 61: 4829(1939) and U.S. Pat. No. 2,487,890 (1950) showed that replacement ofethanol with ethylene glycol resulted in both an increase in conjugationin less time. U.S. Pat. No. 2,350,583 and British Patent No. 558,881(1944) achieved conjugation by reacting fatty acid soaps of an oil withan excess of aqueous alkali at 200-230 degrees C. and increasedpressure.

Among the processes known to effect isomerization without utilizing anaqueous alkali system, is a nickel-carbon catalytic method, as describedby Radlove, et al., Ind. Eng. Chem.38: 997 (1946). A variation of thismethod utilizes platinum or palladium-carbon as catalysts.

Purified conjugated linoleic acid (“CLA”) has recently been shown inseveral studies to have unique properties when used as a food additive.Purified CLA appears to affect fat deposition in animals. Purified CLAboth increases the lean to fat ratio, effectively reducing body fat, andincreases feed conversion efficiency. An additional advantage of feedingCLA is that it appears to modulate immune responses under certainconditions. In laboratory animal studies CLA has been shown to preventweight loss due to immune stimulation and to treat immunehypersensitivity.

The purified CLA utilized in prior studies as an animal feed additivewas obtained by small scale laboratory procedures involving productionof CLA from highly purified linoleic acid. Laboratory and pilot scaleoil refining systems have been described for preparation of purifiedseed oils. For example Sullivan, J. Am. Oil Chemists' Soc., 53: 359(1976), describes a laboratory semi-pilot steam refining system madeentirely of glass.

While these systems are adequate for producing quantities of conjugatedfatty acids for laboratory studies, or even clinical trials, they arenot suitable for commercial scale bulk production. On the other hand,the large scale systems available to produce industrial quantities ofconjugated acids, as in classical drying oils, cannot be runinexpensively enough to produce material for bulk animal feeds. Thestandard degumming, refining, and dehydration steps necessary to obtainnutritionally safe edible conjugated oils for livestock feeding, areprohibitively complex and expensive. (See Braae, J. Am. Oil Chemists'Soc., 53: 353 (1976) for a discussion of complex degumming processes aspracticed on a commercial scale in Europe). Also there are significantlosses of product through polymerization of conjugated fatty acids ortheir precursors at high temperatures.

Economical CLA production in commercial quantities for use in domesticfood animal feeds is a desirable objective in light of the nutritionalbenefits realized on a laboratory scale. Preferably, the CLA is produceddirectly from a source of raw vegetable oil and not from expensivepurified linoleic acid. Further, the process must avoid cost generatingsuperfluous steps, and yet result in a safe and wholesome productpalatable to animals.

SUMMARY OF THE INVENTION

In the present invention, a feed safe conjugated linoleic acid ismanufactured according to a method otherwise used for producing anindustrial grade conjugated product for use in paint and varnish.Typically, residues (i.e. the chemically modified end products resultingfrom heat and pressure) derived from non-oil components of seed oils,such as sterols and phosphatides, form unpalatable, or even toxicby-products under processing conditions. Generally seed oils such ascorn or soy bean oil must be extensively degummed, and the sterols andphosphatides are meticulously removed in a series of purification stepsto avoid fouling of equipment, and to recover a wholesome product. Inaddition to removal of impurities and by-product polymerized orcarmelized material during processing, it is necessary to acidify andfinally distill the oil to obtain product of requisite purity for use infood. Subjecting the oil to isomerization causes further impurities, andrequires even more rigorous decontaminating and by-product removal.

Surprisingly, the Applicant has discovered that a complex purificationscheme for producing a feed safe conjugated linoleic-containing oil isnot necessary, if the starting material is an oil having less than 0.5percent phosphatides, and an unsaponifiable sterol fraction containingless than 20 percent each of campesterol and stigmasterol. According tothis criteria, sunflower and safflower oil are suitable starting oilsfor production of the present feed safe CLA enriched oil, but soybeanoil or corn oil are not suitable because of the high unsaponifiablecontent, and also high levels of linolenic acid that tends to readilypolymerize. It is further desirable to have a starting oil with a highlinoleic acid content, so that the final product has a correspondinglyhigh CLA content.

The present invention encompasses the new use in domestic animal feed ofconjugated linoleic acid produced from a seed oil, especially sunflowerand safflower oils, but not soybean or corn oils, having a linoleic acidcontent of at least 50 percent produced by an industrial scale processin which the crude oil is subjected to the steps of solvent extracting,as with hexane, alcohols, or polyols known in the art, fat splitting,treating with aqueous alkali to effect at least 50 percent isomerizationof the double bonds of linoleic acid to form conjugated linoleic acid atlow temperatures below about 230 degrees F., and preferably below about215 degrees F., acidifying with a mineral acid, and separating the oilfraction from the majority of the aqueous fraction without adistillation step.

In the conjugation of linoleic by isomerization of the double bonds, thefat splitting step releases the free fatty acids from the glycerolbackbone molecule. After the alkali treatment step followed byacidification, several water wash steps may be required to remove salts,and then the water content of the oil fraction can be reduced (aftersimple decanting the upper fat layer) by conventional centrifugationmethods to a content of less than 10 percent. The presence of some waterwill not interfere with animal feed formulating. In fact, the presenceof some water aids the mixing and homogenization step, and provides asource of steam during extrusion.

The animal feeds of the present invention are compounded from theconventional ingredients in rations typical for the species and age ofthe domestic animal to be fed, in addition to from 0.2 to 5.0 percent ofa sunflower or safflower oil having a total C18:2 content of 50-80percent in which at least 50 percent of the linoleic acid has beenisomerized to the conjugated linoleic acid form. Such feeds retain theirpalatability and wholesomeness even though the CLA containing oil isobtained by an industrial process normally reserved for production ofdrying oils for paint and varnish. One principal advantage in this newuse, is that animal feeds containing nutritionally effective amounts ofCLA to achieve reduced body fat content, and firmer fat content in pork,become economically feasible when the CLA can be manufactured inquantities of at least 5 tons per batch or continuous uninterrupted run,without expensive purification and distillation steps.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention relates to the large scale, commercial productionof an edible conjugated fatty acid product from crude extractedsunflower or safflower oil. Processes for conjugating polyunsaturatedfatty acids have been developed by the paint and varnish industry.Conjugated fatty acids were required for the production of drying oils.These drying oils need not be of edible grade, and therefore nopurification is required to remove impurities which do not affect theirdrying function. Recently, purified conjugated linoleic acid (“CLA”) hasbeen shown to be effective in increasing feed efficiency and increasingthe lean to fat ratio of animals. CLA has been shown to be effective inincreasing the lean to fat ratio in animals as disclosed in U.S. Pat.No. 5,554,646, increasing the feed efficiency of animals as disclosed inU.S. Pat. No. 5,428,072, and tempering adverse effects of the immuneresponse as disclosed in U.S. Pat. Nos. 5,430,066 and 5,585,400. Theforegoing patents are herein incorporated by reference. In order torealize the commercial potential of CLA for these purposes, it isnecessary to produce large quantities of a CLA product at a low cost sothat it can be adapted to domestic animal feed rations.

Various methods of producing conjugated double bonds by alkaliisomerization are known in the art. U.S. Pat. No. 2,350,583 (Bradley,1944) describes a method of producing conjugated fatty acids by aqueousalkali isomerization. This method resulted in the conjugation of about50% of the double bonds present in the polyunsaturated fatty acids used.U.S. Pat. No. 2,242,230 (Burr et al., 1941) describes a method ofnon-aqueous alkali conjugation of fatty acids, resulting in theconjugation of approximately 100 percent of the double bonds in thepolyunsaturated fatty acids studied. Another process resulting in theefficient formation of conjugated double bonds is described in U.S. Pat.No. 4,381,264 (Struve, 1983). There, the inventors treat polyunsaturatedfatty acids with SO₂ in the presence of substoichiometric amounts ofsoap forming bases. Perhaps the most commercially viable method forproducing large quantities of conjugated fatty acids is the continuousflow aqueous alkali isomerization process described in U.S. Pat. No.4,164,505. This process results in essentially all available doublebonds being conjugated in a short reaction time. The foregoing patentsare incorporated herein by reference.

The present invention describes the use as a feed ingredient of a CLAproduced by a combination of the continuous countercurrent fat-splittingprocess and the continuous flow alkali isomerization process.

CLA, so produced, is a mixture of the conjugated isomers ofpolyunsaturated fatty acids found in sunflower or safflower oil.Therefore, the conjugated fatty acids will contain conjugated isomerspredominantly of linoleic acid and to a lesser extent linolenic acid.CLA is a mixture of one or all of the isomers of octadecadienoic acidincluding the cis-9, trans-11; cis-9, cis-11; trans-9, cis-11; trans-9,trans-11; cis-10, cis-12; cis-10, trans-12; trans-10, cis-12; andtrans-10, trans-12 isomers. The cis-9, trans-11 and trans-10, cis-12isomers are thought to possess most of the biological activity.Preparations of CLA which contain primarily these isomers are thuspreferred. In general, it is preferred that the fatty acid preparationcontain at least 50% CLA and have a ratio of cis-trans isomers of CLA totrans-trans isomers of CLA of about 5.1 to 8.1.

Crude sunflower or safflower oil is the preferred fatty acid source forproducing CLA. Sunflower oil contains a high amount of linoleic acid(about 65% on average). Safflower oil typically contains even higheramounts (greater than 70%). Preferably, a hexane extract of crude,non-degummed oil is the starting substrate for conjugated fatty acidproduct CFAP production. This extract is commercially available and isthe same quality as the oil used as the starting point for edibleproducts. The ability to use raw sunflower or safflower oil as thestarting substrate provides an important economic advantage because itis less expensive than refined sunflower oil.

Applicants have discovered that other raw oils, such as raw corn andsoybean oils, are not suited to the present new use of CLA in bulk feedsbecause of the production of polymerized products during the fatsplitting and conjugation processes, and because of the high phosphatidecontent. Also, certain sterols such as campesterol and stigmasterol areknown to have a tendency to foul processing equipment during conjugationand plug nozzles during materials transfer. The polymerizationby-products also result in loss of yield from these other oils, eventhough at first glance the other oils may seem to have more desirableproperties. Corn oil (about 56% linoleic acid) and soybean oil (about50-55% linoleic acid) have comparable linoleic acid contents as comparedto sunflower oil (about 60% linoleic acid). These oils are inexpensiveand large quantities are available, which make them attractivecandidates as a potential source of CLA for bulk feeds. However, theiruse for commercial CLA production is substantially lower per unitquantity of oil because the ultimate yields of CLA are lower than forsunflower or safflower oil, and because of the added expense foradditional cleaning and purification steps.

Heat sensitive triglycerides containing multiple double bonds areabundant in oils having an iodine value above 120. Oils containing suchheat-sensitive triglycerides have a tendency to form polymers whensubjected to continuous countercurrent fat-splitting. These polymersbecome insoluble in oil and will foul equipment, resulting in loweredefficiencies of splitting and yields. Sunflower oils are classified asheat-sensitive because of their high linoleic acid content and iodinenumber. Sunflower oil has an iodine number of 130; safflower oil ofabout 145. Soybean oil has an iodine number of about 132, and corn oilhas an iodine number of about 130. All these oils have high linoleicacid contents and iodine numbers above 120, thus belonging to theheat-sensitive group. It is therefore surprising that sunflower andespecially safflower oils can be split and conjugated by commercialprocesses with few processing complications.

The second cause of lower yields relates to the level of impuritiespresent in unrefined oil. Crude oils contain relatively high amounts ofvarious impurities such as phospholipid, proteinaceous and mucilaginousmatter, carbohydrates, pigments, waxes and insoluble. It is normallynecessary to degum and then alkali or mechanically refine these oils toremove the impurities. Degumming involves treating the crude oil withwater to hydrate and precipitate phosphatides and gummy mucilaginoussubstances. The prevalent phosphatides are phosphatidylethanolamine,phosphatidyliniositol and phosphatidylcholine. The phosphatide contentof sunflower and safflower oils is about 0.4 to 1.0% as reported inKlein and Crauer, JAOCS 51:382A-385A and Burkhardt, JAOCS 48:697-699(1971), respectively. In contrast, the phosphatide content of soybeanoil is about 1.5-2.5% as reported in the Handbook of Soy Oil Processingand Utilization, Erickson et al. eds., AOCS, Champaign, 1980. For crudeoils with low amounts of these substances, such as sunflower andsafflower oils, proceeding can advance directly to caustic refining,after degumming.

As described above, oils are generally degummed by precipitation afterhydration with water. It can be expected that gums in the crudesunflower oil utilized in the present invention would be hydrated duringboth the fat-splitting and aqueous isomerization processes. Suchprecipitates may be the cause the fouling of the equipment. Sunfloweroil and safflower oil generally contain similar amounts of phosphatidesand could be expected to behave similarly in processing.

The presence of phosphatides in the crude oil also raises otherconcerns. It is well known in the art that phosphatides in oils may becharred when subjected to steam refining or deodorization and bleaching.These phosphatides may be present in the oil even after repeatedtreatment with caustic soda. The residual phosphatides cause poor tasteand low oxidative stability as discussed in Braae, JAOCS 53:353-357(1976). The counter-current fat-splitting and continuous flow aqueousisomerization processes utilized in most modern processes share severalcommon aspects with steamrefining and deodorization including operationat high temperatures and the presence of steam. Therefore, it could beexpected that phosphatide residues present with the free fatty acidsproduced by fat-splitting and carried over to and not removed by theisomerization process would cause poor taste and oxidative instabilityin the CLA containing oil. For a comparison of sunflower/safflower oiland corn/soybean oil, refer to Table 1.

COMPARISON OF CONTAMINANTS Phosphatides Soybean 1.5-3.0% Sunflower .4-1% Sunflower  .4-1% Sterols (unsapanifiables by percent) SoybeanSunflower Sunflower Campesterol 20* Campesterol 8 Campesterol 13Stigmasterol 20 Stigmasterol 8 Stigmasterol 9 β-Sitosterol 53β-Sitosterol 60 β-Sitosterol 52 Δ⁵ Avensterol 3 Δ⁵ Avensterol 4 Δ⁵Avensterol 1 Δ⁷ Stigmasterol 3 Δ⁷ Stigmasterol 15 Δ⁷ Stigmasterol 15 Δ⁷Avenasterol 1 Avenasterol 4 Avenasterol 3 Percentage of 0.36 percenttotal Total *May not equal 100 0.36% total in oil 0.36% 0.36% SoybeanSunflower Sunflower Iodine Value 134.6 135.4 143.6 Saponification 190.7190.6 190.3 value Unsaponification   .6   .7   .6 value

The first step in the production of bulk animal feed containing CLA ishydrolysis of the raw sunflower oil to form free acids and glycerol. Thepreferred fat-splitting process is a version of the Colgate-Emeryprocess described in Sonntag, Fatty Acids in Industry, Fat Splitting andGlycerol Recovery, Johnson and Fritz, eds., Marcel Dekker, Inc., NewYork, pp 23-72 (1989), incorporated herein by reference. This processinvolves the countercurrent reaction of water and fat under hightemperatures and pressures.

The equipment used for this process is standard in the industry. Theequipment consists of a highly elongated, cylindrical-shaped tower about20 to 48 inches in diameter and 60 to 80 feet high. The tower is made ofstainless steel or some other corrosion resistant material and canwithstand operating pressures of about 750 psig.

In operation, the raw sunflower or safflower oil is pumped into thetower by means of a sparge ring about 3 feet from the bottom of thetower. Water is introduced near the top of the column at about 40 to 50%of the weight of the fat. The sunflower oil rises through the hotglycerol-water collecting section at the bottom of the column and passesthrough the oil-water interface into the continuous phase where thehydrolysis takes place in the oil layer. Direct injection of highpressure steam is used to maintain the temperature at 250° C. Pressureis maintained at about 700 to 750 psig.

Pressure in the column is maintained by means of a back-pressure controlvalve in the fatty acid discharge line. The level of the interface ismaintained by controlling the discharge of the water phase. Closecontrol of the heat exchange at each end of the column is essential forefficient separation because of the solubility of water in fatty acidsand of the fatty acids in glycerine water at the extremely highoperating temperatures.

The second major step in the process is conjugation. Preferably, thecontinuous flow aqueous alkali isomerization process is used. Thisprocess is described in U.S. Pat. No. 4,164,505, incorporated herein byreference.

The alkaline reagent used in the process is any water soluble alkalimetal hydroxide, for example NaOH or KOH. The alkali must be providedwell above stoichiometric excess, preferably greater than about a50-100% excess.

The fatty acids derived from the continuous countercurrent fat-splittingprocess are charged with the metal hydroxide into a flow reaction zonemaintained in many conventional processes at a pressure of about 25-300psi and a temperature of about 230° C. In the recommended method ofisomerization, low temperatures in the 210-220° C. range should bemaintained to avoid predominance of trans isomers. Retention times maybe increased commensurating to retain yields. Sufficient water must beadmitted to the flow reaction zone so that the alkali metal salts whichare formed remain in solution. The total time in the reaction zone ispreferably about 30 minutes, or longer at decreased temperatures.Typical flow rates are about 10 liters/minute. The flow reaction zonecan generally take the from simple tubular flow reactor provided with aninlet for feeding in the sunflower fatty acids, and outlet for removingCFAP, and a means to monitor the composition of the reaction product.

Next, the preparation is acidulated in a batch reactor. Preferably,diluted sulfuric acid is added to the mixture to neutralize the strongalkali. The bottom layer containing sodium sulphate is removed. Then,the remaining fatty acid layer is washed with water and dried under avacuum at about 80° C. to 100° C. For the production of edibleconjugated fatty acid product, a distillation step is not needed.

Example 1 shows the composition of a typical CLA-containing isomerizedsunflower oil produced by the above processes. The ratio of cis-trans totrans-trans isomers was greater than 7:1.

This oil produced by the combination of the continuous countercurrentfat-splitting and continuous flow alkali isomerization processes may beadded to animal feed formulations as a source of CLA.

Many different feed rations may be formulated for animals from manydifferent feed ingredients. Rations are generally formulated toprovide-nutrients in accordance with National Research Councilstandards. The feedstuffs used in the ration are chosen according tomarket price and availability. Thus, some components of the ration maychange over time. In the feeds of the present invention, the ration willalways contain CLA-containing isomerized sunflower or safflower oil in aconcentration of 0.05-5.0 percent, but other components may vary overtime based on the price of the component. For discussions on feed rationformulation, actual rations and NRC guidelines, see Church, LivestockFeeds and Feeding, O&B Books, Inc., Corvallis Oreg. (1984) and Feeds andNutrition Digest, Ensminger, Oldfield and Heineman eds., EnsmingerPublishing Corporation, Clovis, Calif. (1990), incorporated herein byreference.

The animal feed rations of the present invention may be characterizedaccording to NRC requirements. NRC requirements may be found in Church,Livestock Feeds and Feeding, O&B Books, Inc., Corvallis Oreg. (1984), orother nutritional standards. Hog and other animal rations aretraditionally balanced using the protein and energy requirements, andthen adjusted if needed to meet the other requirements. The hog andother feeds of the present invention will contain about 0.05% to 5%lipids plus other feed materials necessary to balance the feed to meetthe NRC requirements for the different stages of growth and maintenance.Preferably, the ration will contain about 0.1 to 1.0% CLA-containingisomerized hydrolyzed oil and most preferably about 0.25-0.5%. Theamount of oil incorporated into the ration is not critical as long as itis enough to be effective in decreasing body fat and increasing feedefficiency or eliciting other desirable responses.

The relative amounts of protein and energy are adjusted to reflectNutritional Standards requirements. The amounts of feed components willvary with the stage of animal fed. A growing ration for young animalswill have higher protein levels, while a finishing ration for finishinganimals for market will have higher energy values which are supplied bycarbohydrates. For example, hog prestarter, starter and grower-finisherrations will generally contain about 20-24% protein, 18-20% protein and13-17% protein respectively. In some feeding situations, care must betaken to provide the appropriate amino acids as well as overall proteincontent. For example, hogs fed large amounts of corn must have adequatelysine made available in the ration. In most animal diets, energyrequirements are met by starches in cereal grains. Energy requirementsmay also be met by addition of fat to the ration. In the presentinvention, the CFAP provides part of the energy requirement. Addition offat to hog rations has been proven to increase growth rate slightly.Feed intake is reduced and feed efficiency is improved when fat is addedto the ration. Since feed intake is reduced when fat is added, itimportant to increase the level of protein so that the daily intake ofprotein is maintained. In general, the protein level should be increasedby 0.2% for every 1% addition of dietary fat.

The CLA-containing isomerized hydrolyzed oil in the rations of thepresent invention meets the definition of hydrolyzed fat contained inthe 1997 Official Publication, Association of Feed Control OfficialsIncorporated (1997). Feed grade hydrolyzed soap making. It consistspredominantly of fatty acids, and must contain not less than 85% fattyacids, not more than 6% unsaponifiable matter, and not more than 1%insoluble impurities. The oil used in the present invention ishydrolyzed sunflower oil (fat) produced by the combination of thecommercial countercurrent fat-splitting and continuous flow alkaliisomerization processes, or commercial variation thereof in common use.During these processes, the raw sunflower or safflower oil is hydrolyzedand conjugated to form a hydrolyzed fatty acid product.

Other ingredients may be added to the feed ration. These ingredientsinclude, but are not limited to, mineral supplements such as calcium,phosphorus, salt, selenium and zinc; vitamin supplements such asVitamins A, B, D, E, and K; amino acid supplements such as lysine;coccidiostats, except in hog feeds, or growth promoters such asbacitracin or virginamycin; and other active drugs such aschlortetracycline, sulfathiozole, and penicillin. For vitamin, mineraland antibiotic supplement formulation see Church, Livestock Feeds andFeeding, O&B Books, Inc., Corvallis Oreg. (1984).

In a preferred embodiment, the oil is incorporated into a pelleted feedfor administration to domestic animals. Pelleted feed is created byfirst mixing feed components and then compacting and extruding the feedcomponents through a die with heat and pressure. The feed is pelleted bymethods known in the art, which are described in MacBain, PelletingAnimal Feed, American Feed Manufacturers Association, Arlington, Va.(1974), incorporated herein by reference. When incorporating added fatinto pelleted feed, caution is needed in order to avoid making mealypellets. Generally, only about 2% of the fat is added during pelleting,with the rest added after the pellets have cooled. Alternatively, theCLA-containing isomerized hydrolyzed oil could be added directly to asimple crushed or blended feed ration. Alternatively, the CLA-containingisomerized hydrolyzed oil could be added directly to a simple crushed orblended feed ration.

The oil and the feed containing the oil may be stabilized by theaddition of antioxidants. Therefore, antioxidants may be added aschemical preservatives in accordance with F.D.A. regulations as listedin the 1997 Official Publication, Association of Feed Control OfficialsIncorporated (1997), herein incorporated by reference. Suitableantioxidants include, but are not limited to: Lecithin, tocopherols,ascorbate, ascorbyl palmitate and spice extracts such as rosemaryextract.

Rations containing edible CFAP may also be formulated for animals otherthan hogs. The amount of CFAP administered is not critical as long as itis enough to be effective in decreasing body fat and increasing feedefficiency or other benefits. The feeds are formulated as above, andtailored to the requirements of the animal to be fed in accordance withNRC guidelines. For example, feeds may be formulated for dogs, cats,poultry and cattle. Various rations are given in the examples. Variousfeed formulations, balancing methods and requirements for these animalsare discussed in Church, Livestock Feeds and Feeding, O&B Books, Inc.,Corvallis Oreg. (1984) and Feeds and Nutrition Digest, Ensminger,Oldfield and Heineman eds., Ensminger Publishing Corporation, Clovis,Calif. (1990), incorporated herein by reference. It should be borne inmind that feed companies and livestock producers develop their ownnutritional requirements based on historical results. The presentinvention makes the use of CFAP possible in these various feeds becausethe CFAP may be produced economically in bulk quantities.

The oil containing feed must be palatable to domestic animals,especially hogs consuming the feed. Hogs are known to have acuteolfactory senses and to refuse feed with undesirable odors. Therefore,it is surprising that a process used to produce drying oils in varnishesand paints can be adapted to produce a feed additive that is both safeto feed and palatable to hogs.

The CLA may also be utilized in oil form produced by reesterification toglycerol, or a powder or gel of the free fatty acid. Additionally, theCLA may be derivitized to form a non-toxic salt, such as a potassium orsodium salt, which is formed by reacting chemically equivalent amountsof the free acids with an alkali hydroxide at a pH of about 8 to 9.

The following Examples further illustrate the invention.

EXAMPLE 1

Raw sunflower oil extracted by conventional hexane methods was subjectedto continuous countercurrent fat-splitting at high pressure (50 bar) andhigh temperature (250° C.). The free fatty acids were then conjugated ina continuous flow reactor with addition of NaOH at low temperature (220°C.) for approximately 30 minutes. The conjugated fatty acid product wasacidulated with sulfuric acid, the fatty acid layer retained and washedwith water, and dried under a vacuum at about 80° C. to facilitate GCanalysis the fatty acid product was distilled. The distillate wasanalyzed by gas chromatography with a Perkin Elmer Autosystem GC. Thecombination continuous countercurrent fat splitting and continuousalkali isomerization process resulted in the production of a CFAPcontaining predominantly cis-trans isomers of CLA as shown in Table 1.Table 2 compares just the components of CLA.

TABLE 2 Components of CFAP Component Name Height (uV) Area (%) c 16:027040.43 4.51 c 18:0 13872.05 3.03 c 18:1 c9 23310.18 4.74 c 18:262558.95 21.06 c9,t11/t9, unknown c 18:2 unknown 46693.44 12.41 c 18:2tl0 74414.84 14.71 c12/c10, t12 5796.95 .86 c 18:2 c9, c11 10147.05 1.63c 18:2 c10, c12 12555.32 2.25 c 18:2 25729.06 4.60 t9,t11/t10, t12

TABLE 3 CLA Components Time Component Height Peak # (min) Name (uV) Area% 19* 77.636 c9,t11/t9 62558.95 35.54 c10 20 78.254 46693.44 20.96 2178.550 t10 74414.84 24.84 c12/c10, t12 22 78.780 5796.95 1.46 23 78.952c9,c11 10147.05 2.75 24 79.194 c10,c12 12555.32 3.79 25 79.365 5944.401.36 26 79.810 1581.26 .44 27 80.208 4104.44 1.09 28 80.506 t9 25729.067.76 t11/t10, t12 *Peak #19 is c9,t11 coeluting with t8,c10. Peak #2 isan 11,13 isomer.

EXAMPLE 2 PIG STARTER RATIONS Ingredients lbs. kgs. Corn, yellow (8.4%protein) 1067 484.7 Soy bean meal, solvent 570 259 extracted, dehulled(47% protein) CFAP 5 2.3 Whey, dried (12.0% protein) 300 136 Dicalciumphosphate 24 11 Limestone 16 7 Iodized salt 5 2 Trace mineral premix 5 2Vitamin premix 8 4 Totals 2000 908

EXAMPLE 3 GROWER-FINISHER RATIONS FOR PIGS (FROM 40-240 LBS [18-109KGS]) Ingredients lbs. kgs. Corn, yellow (8.4% protein) 1566 Soybeanmeal, solvent extracted 380 (44% protein) CFAP 5 Dicalcium phosphate 21Limestone 15 Iodized Salt 5 Trace Mineral Premix 3 Vitamin Premix 3Total 2000

EXAMPLE 4 PIG GROWER FINISHER RATIONS (FOR PIGS 121-240 LBS [55-109KGS]) Ingredients lbs. kgs. Corn, yellow (8.4% protein) 1687 Soybeanmeal, solvent extracted 265 (44% protein) CFAP 5 Dicalcium phosphate 18Limestone 15 Iodized salt 5 Trace mineral premix 2 Vitamin premix 3Total 2000

EXAMPLE 5 COMPOSITION AND ANALYSIS OF PIG TRACE MINERAL REMIX ElementSource Amount (lbs) Copper (Co) Copper Sulfate 1.500 Iodine (I)Potassium Iodide 0.010 Iron (Fe) Ferrous Sulfate 25.000 Manganese (Mn)Manganese Sulfate 2.500 Selenium (Se) Sodium Selemite) 0.025 Zinc (Zn)Zinc Sulfate 25.000 Carrier 45.965 Total 100.000

EXAMPLE 6 COMPOSITION OF PIG VITAMIN PREMIX Vitamins Amount EssentialVitamin A (million IU) 5.0 Vitamin D (million IU) 0.6 Vitamin E(thousand IU) 26.0 Niacin (g) 25.0 d-Pantothenic acid (g) 20.0Riboflavin (g) 6.0 Vitamin B-12 (mg) 25.0 Optional Biotin (g) 0.3Menadione (g) 4.0 Carrier to 10 lbs Total 10.0

EXAMPLE 7 18% PROTEIN LAYER RATIONS FOR HENS lbs. kgs. IngredientsGround yellow corn 1242 564.5 CFAP 5 2.3 Alfalfa meal, 17% 25 11.3Soybean meal, dehulled 451.6 205.3 Meat and bone meal (47%) 50 23.0DL-methionine 1.0 .5 Dicalcium phosphate 7 3.1 Ground limestone 174 79.1Iodized salt 7 3.1 Stabilized yellow grease 37 17.2 Mineral and vitaminsupplements Calcium pantothenate (mg) 5,000 Manganese (g) 52 Selenium(mg) 90.8 Zinc (g) 16 Vitamin A (IU) 6,000,000 Vitamin D₃ (IU) 2,000,000Choline (mg) 274,000 Niacin (mg) 12,000 Riboflavin (mg) 2,000 VitaminB-12 6 Total 2000 909.4

EXAMPLE 8 STARTER AND FINISHER RATIONS FOR BROILERS Starter (up to 24Finisher (25 days to days) market) Ingredients lbs. kgs. lbs. kgs.Ground yellow corn 1,106 503 1235 561 CFAP 5 2.3 5 2.3 Soybean meal. 605275 120 191 dehulled Alfalfa meal, 17% — — 25 11 Corn gluten meal, 50 2375 34 60% Fish meal, herring, 50 23 50 23 65% Meat and bone meal, 50 2350 23 47% Dicalcium phosphate 10 4 9 4 Ground limestone 16 7 14 6.3DL-methionine 0.8 0.3 — — Stabilized yellow 101 45.7 110 49.4 greaseIodized salt 7 3 7 3 Mineral and vitamin supplement Calcium pentothenate5,000 5,000 (mg) Manganese (g) 75 75 Organic arsenical 0.1 0.1supplement Selenium (mg) 90.8 90.8 Zinc (g) 30 30 Vitamin A (IU)4,000,000 4,000,000 Vitamin D (IU) 1,000,000 1,000,000 Vitamin E (mg)2,000 2,000 Vitamin K (mg) 2,000 2,000 Choline (mg) 503,000 672,000Niacin (mg) 20,000 20,000 Riboflavin (mg) 3,000 3,000 Vitamin B-12 (mg)12 12 Total 2000.9 909.3 2000.1 909.5

EXAMPLE 9 GROWER/FINISHER TURKEY RATIONS Finisher Grower (8-16 (16weeks- weeks) market) lbs. kgs. lbs. kgs. Ingredients Ground yellow corn1194 595 1490 677.2 Wheat middlings 50 23 — — Alfalfa meal, 17% 25 11.325 11.3 Soybean meal, 570 259 335 152.3 dehulled Meat and bone meal, 5023 50 23 47% Dicalcium phosphate 32 14.5 23 10.5 Ground limestone 14 617 8 Stabilized yellow 45 20.7 45 20.7 grease CFAP 5 2.3 5 2.3 IodizedSalt 10 4.5 10 4.5 Mineral and vitamin supplements Calcium pantothenate4,500 4,500 (mg) Manganese (g) 30 30 Selenium (mg) 181.6 181.6 Zinc (g)30 30 Vitamin (IU) 1,500,000 7,500,000 Vitamin D (IU) 1,700,0001,700,000 Vitamin E (IU) 10,000 10,000 Biotin (mg) 100 100 Choline (mg)388,000 417,000 Niacin (mg) 46,000 48,000 Riboflavin (mg) 5,000 5,000Vitamin B-12 6 6 Total 2000 909.3 2000 909.3

DRY DOG FOOD FORMULA Ingredients Formula 1, % Formula 2, % Meat and bonemeal, 50% 8.0 15.0  CP Fish meal, 60% CP, low 5.0 3.0 fat Soybean meal,44% CP 12.0  — Soybean meal, 50% CP — 19.0  Wheat germ meal, 25% CP 8.05.0 Skimmed milk, dried 4.0  2.75 Cereal grains, mixed 51.23 — Corn,flaked — 23.25 Wheat bran 4.0 — Wheat, flaked — 23.35 Animal fat  1.75 2.75 CFAP  .25  .25 Steamed bone meal 2.0 — Brewers yeast 2.0 5.0Fermentation solubles, 1.0 — dehydrated Salt and trace minerals 0.5 0.5Vitamin mixture  0.25  0.25 Ferric oxide  0.02 — Total 100.00  100.00 

SEMI-MOIST DOG FOOD FORMULAS Ingredients Formula 1, % Formula 2, % Soyflakes 30.9  33.5  Meat byproducts, 70% moisture 32.0  — Meat and bonemeal, dehydrated — 7.3 Water — 25.6  Sugar 21.0  21.0  Calcium andphosphorous 3.3 — supplement Soybean hulls 3.1 3.1 Skimmed milk, dried2.5 — Propylene glycol 2.1 2.1 Sorbitol 2.0 2.0 Animal fat  .75  3.95CFAP  .25  .25 Emulsifiers 0.9 — Potassium sorbate  0.35  0.35 Salt 0.60.6 Vitamins  0.25  0.25 Total 100.000 100.000

What is claimed is:
 1. An animal feed made by the method comprising: a)providing a seed oil having a linoleic acid content of at least 50percent, said seed oil selected from sunflower oil and safflower oil; b)subjecting said seed oil to solvent extraction, fat splitting and alkalitreatment under conditions such that an isomerized preparation iscreated, wherein at least 50 percent isomerization of linoleic acid toconjugated linoleic acid is obtained; c) treating said isomerizedpreparation under conditions such that aqueous and non-aqueous fractionsare generated, said non-aqueous fraction comprising said conjugatedlinoleic acid; d) separating said non-aqueous fraction from said aqueousfraction; and e) formulating an animal feed with said non-aqueousfraction.
 2. An animal feed made by the method comprising: a) providinga seed oil selected from sunflower oil and safflower oil; b) subjectingsaid seed oil to conditions such that an isomerized preparation iscreated comprising conjugated linoleic acid; c) treating said isomerizedpreparation under conditions such that aqueous and non-aqueous fractionsare generated, said non-aqueous fraction comprising said conjugatedlinoleic acid; d) separating said non-aqueous fraction from said aqueousfraction without distillation; and e) formulating an animal feed withsaid non-aqueous fraction.